The blender won't start up
My instance of Blender mysteriously stopped working on Win 10 64-bit.  The Visual Studio debugger said, "unhandled exception 0xc0000904."  

I uninstalled Blender 2.75, re-installed the MS Visual Studio redistributable (msvcr120.dll), installed Blender 2.77, went through the usual windows service troubleshooting steps starting from a clean boot.  All no help.  

I finally ran the Program Compatibility troubleshooter, the diagnostics log in %appdata%/temp said "python incompatible".  

So I deleted the PYTHONPATH environment variable.  Voila! Now Blender starts fine.